fix(canonicalize): prevent collapse cache pollution across calls

CHANGELOG.md

@@ -32,6 +32,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Improve performance Oxide scanner in bigger projects ([#19632](https://github.com/tailwindlabs/tailwindcss/pull/19632))
 - Ensure import aliases in Astro v5 work without crashing ([#19677](https://github.com/tailwindlabs/tailwindcss/issues/19677))
 - Allow escape characters in `@utility` names to improve support with formatters such as Biome ([#19626](https://github.com/tailwindlabs/tailwindcss/pull/19626))
+- Fix invalid cache during subsequent canonicalization calls ([#19675](https://github.com/tailwindlabs/tailwindcss/pull/19675))
 
 ### Deprecated
 

packages/tailwindcss/src/canonicalize-candidates.test.ts

@@ -1163,3 +1163,46 @@ describe('options', () => {
     expect(designSystem.canonicalizeCandidates(['m-[16px]'])).toEqual(['m-[16px]']) // Ensure options don't influence shared state
   })
 })
+
+// https://github.com/schoero/eslint-plugin-better-tailwindcss/issues/321
+test('a subset of classes should be canonicalizable', { timeout }, async () => {
+  let designSystem = await designSystems.get(__dirname).get(css`
+    @import 'tailwindcss';
+  `)
+
+  let options: CanonicalizeOptions = {
+    collapse: true,
+    logicalToPhysical: true,
+    rem: 16,
+  }
+
+  expect(
+    designSystem.canonicalizeCandidates(['underline', 'h-4', 'w-4', 'text-sm'], options),
+  ).toEqual(['underline', 'text-sm', 'size-4'])
+})
+
+test('collapse canonicalization is not affected by previous calls', { timeout }, async () => {
+  let designSystem = await designSystems.get(__dirname).get(css`
+    @import 'tailwindcss';
+  `)
+
+  let options: CanonicalizeOptions = {
+    collapse: true,
+    logicalToPhysical: true,
+    rem: 16,
+  }
+
+  let target = ['underline', 'h-4', 'w-4']
+
+  expect(designSystem.canonicalizeCandidates(target, options)).toEqual(['underline', 'size-4'])
+
+  designSystem.canonicalizeCandidates(['mb-4', 'text-sm'], options)
+  designSystem.canonicalizeCandidates(['underline', 'mb-4'], options)
+
+  expect(designSystem.canonicalizeCandidates(target, options)).toEqual(['underline', 'size-4'])
+  expect(designSystem.canonicalizeCandidates(target.concat('text-sm'), options)).toEqual([
+    'underline',
+    'text-sm',
+    'size-4',
+  ])
+})

packages/tailwindcss/src/canonicalize-candidates.ts

@@ -267,6 +267,8 @@ function collapseCandidates(options: InternalCanonicalizeOptions, candidates: st
         let interestingLineHeights = new Set<string | number>()
         let seenLineHeights = new Set<string>()
         for (let pairs of candidatePropertiesValues) {
+          if (!pairs.has('line-height')) continue
+
           for (let lineHeight of pairs.get('line-height')) {
             if (seenLineHeights.has(lineHeight)) continue
             seenLineHeights.add(lineHeight)
@@ -292,6 +294,8 @@ function collapseCandidates(options: InternalCanonicalizeOptions, candidates: st
 
         let seenFontSizes = new Set<string>()
         for (let pairs of candidatePropertiesValues) {
+          if (!pairs.has('font-size')) continue
+
           for (let fontSize of pairs.get('font-size')) {
             if (seenFontSizes.has(fontSize)) continue
             seenFontSizes.add(fontSize)